| Electrical Insulation and Dielectrics
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| Gaseous Dielectrics:
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- Atmospheric air is the cheapest and most widely used
dielectric . Other gaseous dielectrics, used as compressed gas
at higher pressures than atmospheric in power system, are
Nitrogen , Sulphurhexafluoride SF6(an electro-negative gas) and
it's mixtures with CO2 and N2 . SF6 is very widely applied for Gas Insulated Systems (GIS),
Circuit Breakers and gas filled installations i.e. sub-stations and cables. It is being now applied for power transformers also.
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| Vacuum as Dielectric :
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- Vacuum of the order of 10-5 Torr and lower provides an excellent electrical insulation. Vacuum technology developed and applied for
circuit breakers in the last three decades is phenomenon .
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| Liquid Dielectrics:
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- Organic liquids, the mineral insulating oils and
impregnating compounds, natural and synthetic,
of required physical, chemical
and electrical properties are used very widely in transformers, capacitors, cables and circuit breakers.
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| Solid Dielectrics:
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- Very large in number .
- Most widely used are : XLPE, PVC, ceramics, glass,
rubber, resins, reinforced plastics, polypropylene, impregnated paper, wood, cotton, mica,
pressboards, Bakelite, Perspex, Ebonite, Teflon, etc.
- Introduction of nano materials are in offing.
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